This invention relates generally to power regulation and conversion.
When designing power controllers for use in supplying power to a load, solutions to specific problems must be provided before such devices achieve practicality. A first problem is safety. Unless the device isolates the power source from the load, there is an unacceptable risk of electric shock during use. Thus, a given solution must result in sufficient isolation for safety, while providing adequate power to the load.
A second problem is correction for power factor and total harmonic distortion (THD). When power is obtained from a public power grid, power factor must be corrected to prevent large amounts of power which do not register on electric meters from being converted into second third, fifth and higher order haromonics which reflect back into the power grid causing large amounts of THD. Third, sixth, ninth, etc. harmonics heat neutral conductors in wiring and electrical panels, and the primary windings of utility pole or vault transformers and, over time, damage this costly equipment. Second, fifth, eighth etc. harmonics cause counter-rotating magnetic fields in electric motors so they draw more power to do less work, again leading eventually to costly equipment failures.
A third problem is compatibility of the device with different load voltages. Many devices are limited to use where the load voltage remains within a narrow range and thus are not flexible enough to be used in applications where the load voltage does not fall within that range.
Thus, there is a continuing need for power controllers which provide electrical isolation between a load and a power source while still providing adequate power to the load and power factor correction over a wide range of load voltages.
According to the present invention, a power regulation and conversion device is provided. Such a device has particular applicability when incorporated into a battery charger (see U.S. Pat. Nos. 5,087,802 and 6,204,630, each of which is herein incorporated by reference in its entirety) but may also be advantageously used to supply power to other types of loads as well. The provided device includes a boost pre-regulator receiving power from a power source providing an input voltage and an input current, and having compensation networks which are dynamically adjusted for power level, the pre-regulator providing power factor correction to maintain a total harmonic distortion of the input current of 2-3% at full power, and less than 5% at all power levels, while the input voltage is anywhere within the range of 95 to 265 VAC; and a forward converter receiving control from a current-mode controller which is in turn under the control of the boost pre-regulator, in order to achieve substantially constant duty cycle of the forward converter over the entire range of power levels. Alternative embodiments may utilize a single converter to perform both boost pre-regulation and forward conversion on a time-share basis, may provide power factor correction to maintain a power factor of at least 99.9%, and may include a connector sized and dimensioned to electrically couple The power controller to a power source providing an input voltage and input current to the boost pre-regulator.